Preferred obstetrical procedures include monitoring the health of a fetus during delivery by detecting the fetal heartbeat. A miniature electrode assembly is inserted into the vaginal passage and is attached to the scalp or other presented portion of the fetal anatomy. The device senses changes of electrical potential at the skin of the fetus that are caused by heart activity and transmits a varying voltage indicative of successive heartbeats to an external monitoring circuit. The circuit controls a chart recorder and/or other data presenting apparatus at which the fetal heart activity may be monitored by attending medical personnel.
Two signal output wires extend from the miniature heartbeat sensor as the external circuit must reference or compare the voltage at the fetal skin with the voltage at a nearby region of the amniotic fluid. The output wires are interconnected with the external monitoring circuit at a device that is known as a leg plate as it is usually fastened to a maternal leg during use. In addition to serving as a circuit junction the leg plate has an additional electrode which senses voltage variations at the maternal skin. This provides a signal which enables the monitor to distinguish between the fetal heartbeat and the maternal heartbeat.
A typical prior leg plate includes a base which is strapped to the maternal leg by a nurse when it is to be used. The base carries a pair of slidable clips which can be opened by the thumb and fingers to enable insertion of the output wires of the fetal heartbeat sensing electrode assembly. Steel springs bias the slidable clips to closed positions at which the ends of the output wires are clamped against internal electrical contacts. An output cable enables the leg plate to be coupled to the input cable of the monitoring circuit.
Prior leg plates are costly to produce and have not been designed to be treated as a disposable item that can be discarded after a single use. The prior leg plates are also undesirably bulky and mechanically complicated. Set-up procedures and attachment of the device to the expectant mother are more difficult and time consuming than would be desirable. Contamination by body fluids often occurs and the leg plates are difficult to clean which further complicates usage of the conventional leg plate.
The present invention is directed to overcoming one or more of the problems discussed above.